Recently there has been increased interest into molecular glasses that can be coated into amorphous films for applications such as photoresist or molecular optoelectronic devices, including light-emitting diodes, field-effect transistors, and solar cells, as well as in advanced materials for xerography, two-photo absorption, luminescent devices, and photorefraction. One technique that is used in the art is a reverse of the principles of crystal engineering to devise molecules that resist crystallization. Examples of this technique are described in the publications by Eric Gagnon et al: “Triarylamines Designed to Form Molecular Glasses. Derivatives of Tris (p-terphenyl-4-yl) amine with multiple Contiguous Phenyl Substituents.” Organic Letters 201, Vol. 12, No. 3, p 404-407.
The traditional method of optoelectronic devices fabrication such as small molecules organic light emitting diode (OLED) is vacuum deposition of all the layers using a shadow mask to locally pattern the devices. For relatively small devices such as cell phones, tablets and small displays these techniques work very well. However shadow mask technology cannot provide the required uniformity over large areas required for large displays. Thus deposition processes other than thermal evaporation are required. The fabrication of organic semiconductors using inkjet printing is reported in U.S. Pat. No. 6,087,196. Ink of polyvinylcarbazole polymer doped with luminescent dyes such as coumarin 6, coumarin 47 and nile red were printed by inkjet deposition to form patterns of red, green and blue pixels to generate full color displays. One problem associated with this approach is that the dots printed do not have a uniform thickness. Sturm et al in U.S. Pat. No. 7,090,890 describes a process of making semiconductor devices by modifying the properties of a deposited organic film by either adding new components into the film from a top or bottom surface; or by causing components to leave the film from a top or bottom surface. In U.S. Pat. No. 6,066,357 Tang et al reported methods of making full-color organic lightemitting display by inkjet printing of fluorescent dopants selected to produce red, green, or blue light emission from designated subpixels of the display. The dopants are printed sequentially from inkjet printing and subsequently diffused from the dopant layer into the light emitting layer by exposing the light-emitting layer and the dopant layers to vapor of a fluid or fluid mixture. The use of fluid to assist dye diffusion has its drawback. The fluid can affect other layers and degrade the device. Heat-assisted diffusion is an option; but because the glass transition temperature of the layers are designed to be high to ensure thermal stability, the coefficient of diffusion is very low below the glass transition temperature as described in “Anomalous Temperature Dependence of Solvent-Enhanced Dye Diffusion in Polymer Films”, T. Graves-Abe, F. Pschenitzka, J. C. Sturm, Mat. Res. Soc. Symp. Proc. Vol. 725 @ 2002 Materials Research Society.
Most of small molecules OLED materials, including the organic transport materials are not soluble in coating solvents or tend to crystallize in the presence of solvent. Molaire in U.S. patent application Ser. No. 14/467,143, “Charge-transporting Molecular Glass Mixtures, Luminescent Molecular Glass Mixtures, or Combinations Thereof for Organic Light Emitting Diodes and other Organic Electronics and Photonics Applications”, describe charge-transporting and luminescent molecular glass mixtures that are soluble in coating solvents and non-crystallizable. These molecular glass mixtures can be coated by inkjet and other solution process. However it is not practical to coat multi layers without damaging the previously coated layers, unless a solvent barrier layer is utilized. Or it is required to carefully engineer the solubility of each layer. For example the solvent of the secondly-coated layer cannot dissolve the firstly-coated layer; the solvent of the thirdly-coated layer cannot dissolve the secondly-coated layer and so on.
There is a need to develop economical coating processes for large color displays. There is a need to provide organic semiconductor glasses that can be coated from solvent in layers that are not attacked by solvent once dried. There is a need to provide processes that allow solvent coating of multiple thin layers for optoelectronic devices fabrication.
The present invention provides solutions for the above problems.
It is an object of this invention to provide crosslinkable charge-transporting molecular glass mixtures, polymerizable charge-transporting molecular glass mixtures, luminescent molecular glass mixtures, or combinations thereof with the many of the advantages illustrated herein.
It is also an object of this invention to provide crosslinkable charge-transporting molecular glass mixtures, polymerizable charge-transporting molecular glass mixtures, luminescent molecular glass mixtures, or combinations thereof that are readily soluble in common coating solvents, without crystallization.
It is further object of this invention to provide crosslinkable charge-transporting molecular glass mixtures, polymerizable charge-transporting molecular glass mixtures, luminescent molecular glass mixtures, or combinations thereof to enable economical solvent processes for the fabrication of optoelectronic organic films.
Yet another object of this invention is to provide a method for manufacturing optoelectronic organic films having locally modified areas.
Still another object and advantage of the invention is to form an organic film with modified properties by applying dopants in desired places.
A further object and advantage of the invention is the provision of a method for forming an organic film with local modified areas by adding dopants to the film.
Even another object of the invention is to provide a method for locally modifying properties of an organic film without the need for photolithography and etching of the organic film nor the need for contacting the surface of said film with solvents.
A still further object and advantage of the invention is the provision of a method for manufacturing a locally modified organic film without the need for contacting the surface of said film with solvents.
Even an additional object of the invention is to provide a process of forming a locally modified organic film wherein dopant is added to the film in an annealing process at low temperature.